This invention relates to a video signal recording device and method for recording an input video signal with a closed caption character information superposed thereon.
In the United States, in order that persons who have difficulty in hearing as well as persons with a normal healthy body can enjoy a television broadcasting, a closed caption system in which the character information representing audio contents superimposed on a video signal is displayed as a caption has been adopted in a broadcasting and video tape.
In the closed caption system, character information of 16 bits (2 characters) is superimposed on e.g. a 21-th scanning line during a vertical blanking period of each field of the video signal. A television receiver or video tape recorder dealing with the closed caption is equipped with a decoder for the closed caption. The decoder extracts the information (closed caption data, hereinafter referred to as “CC data”) superimposed on the video signal to create the character signal of a character code corresponding to the CC data. The character signal thus created is superimposed on a displayed image. An example of such a decoder for the closed caption is disclosed in the Japanese Patent No. 2657146 and the Unexamined Japanese Patent Application Publication No. Hei7-288785.
The CC data in the closed caption defines not only the character code, but also a control code representative of a command specifying the attribute such as color of a displayed character, position (row and column) of the character, timings of starting to display the character and canceling it, etc. For example, in a television receiver dealing with the closed caption, when the command of starting to display the character is received, the character information corresponding to the CC data detected subsequently is displayed on the screen. When the command of canceling the character is received, the displayed character information is cancelled. When the command of starting to display the character information is received next time, the display of the character information is started.
In a video tape recorder and others, where the video signal with the character information of the above closed caption superimposed thereon is recorded, when the operation of the pause of recording pause/release thereof is carried out, the recorded CC data are discontinuous. For example, in the video tape recorder of a VHS system which is in common use, an analog video signal is recorded on each track of a magnetic tape according to a video synchronizing signal so that the CC data is recorded as a part of the analog video signal. Therefore, immediately after recording is started or release of pause of the recording is performed, the CC data which has been input until immediately before is not recorded, but the continuity of the CC data is lost. When the recorded tape subjected to the pause of recording/release thereof is played back and displayed on the television receiver designed for the closed caption, an inconvenience of disorder of the displayed character information occurred.
FIG. 6 is a view for explaining an example of the operation of pause of recording/release thereof in the video signal including a closed caption. In FIG. 6, the numerals in the CC data denote the frame numbers in a time sequence. This illustrates how the character information corresponding to two characters is transferred in one frame. Where the input image with the CC data which is continuously inputted is recorded, when pause of recording/release thereof is carried out, the CC data are discontinuously recorded before and after the pause point which is a gap of the recording medium. In this case, the recorded CC data may break off from halfway, otherwise may be recorded halfway. In the reproduction of the recorded image, in some cases, when the CC data recorded as described above is decoded to display the character, a string of characters which is composed of incomplete characters or words and is not clear in the meaning was displayed.